Efficient Schemes and Architectures for Check Node Update in Shuffled Min-Sum Decoding of LDPC Codes

By dividing Variable Nodes (VNs) into groups and processing groups sequentially, the Shuffled Min-Sum (SMS) decoding of Low-Density Parity-Check (LDPC) codes achieves a good trade-off between hardware resource and throughput. However, under the grouping strategy where at least one Check Node (CN) has multiple VN neighbors in one group, the CN update of State-Of-The-Art (SOTA) SMS decoding has long latency and high complexity. To address the issue, this paper presents two efficient CN update schemes. The first one uses the first two minimum Variable-to-Check (V2C) message magnitudes in each group and a size-λ Monotone Double-ended Queue (λMDQ), leading to an Improved λMDQ (I-λMDQ) scheme. The second one called the Modified λMDQ (M-λMDQ) scheme uses only the minimum in each group. As a result, our schemes reduce the number of Selection Modules (SMs) required by the CN update to only one. Simulation results show that both of our schemes have comparable error-correction performance to the SOTA schemes. Furthermore, we simplify the SM via a decomposition design and also present the detailed hardware architectures for our schemes. Analysis using the 90nm CMOS technology library shows that, compared to the SOTA schemes, our I-λMDQ scheme reduces the area and latency by up to 75% and 72%, respectively, while improving the throughput by up to 254%. Similarly, our M-λMDQ scheme reduces the area and latency by up to 79% and 70%, respectively, and improves the throughput by up to 229%.